Bitcoin security risk grows with quantum computing advances

Nearly one-third of all Bitcoin in circulation—over 6 million coins worth more than $469 billion at current prices—is already potentially vulnerable to theft if sufficiently powerful quantum computers become a reality, according to research published Wednesday by blockchain analytics firm Glassnode.

The analysis, which examines Bitcoin’s blockchain to identify coins whose public cryptographic keys have already been exposed, found that 6.04 million BTC, or 30.2% of the total issued supply, is exposed to quantum-related risk, News.Az reports, citing Yahoo Finance.

The remaining 13.99 million BTC, the report says, shows no public-key exposure. This estimate is lower than some other assessments, which have placed the figure closer to 7 million BTC.

The concern is rooted in Bitcoin’s underlying security design. Each coin is controlled by a private key paired with a public key that is visible on the blockchain under certain conditions. The theoretical quantum risk is that a sufficiently advanced quantum computer, using Shor’s algorithm, could derive a private key from a known public key.

In such a scenario, any coins whose public keys have already been revealed on-chain could become immediately vulnerable to theft, even without any transaction activity.

Glassnode divides exposed Bitcoin into two main categories. Structural exposure accounts for 1.92 million BTC, or 9.6% of the issued supply. These coins are held in script formats that reveal public keys by design, including early “pay-to-public-key” outputs linked to Bitcoin’s pseudonymous creator Satoshi Nakamoto, legacy multisignature structures, and some newer Taproot-based outputs.

Many of these coins are likely inaccessible in practice, either because they are lost or held in dormant wallets that cannot be moved to safer address formats.

The larger category is operational exposure, which totals 4.12 million BTC, or 20.6% of the supply. These coins were not inherently vulnerable at creation but became exposed through address reuse, a practice in which a wallet receives multiple transactions at the same address and eventually reveals its public key when spending funds, leaving remaining balances exposed.

Within this group, exchanges account for a significant share. About 1.66 million BTC, or 8.3% of total supply, is linked to exchanges—roughly 40% of all operationally exposed Bitcoin. The report highlights uneven exposure across platforms: Coinbase reportedly has about 5% of its labeled holdings exposed, while Binance and Bitfinex show much higher levels at 85% and 100%, respectively.

Glassnode emphasized that the findings should not be interpreted as a measure of exchange solvency or risk ranking, noting instead that the results reflect differences in custody and wallet design. Sovereign holdings appear far safer, with the United States, United Kingdom, and El Salvador showing zero quantum exposure.

The report does not predict when a quantum computer capable of breaking Bitcoin’s encryption will exist, but frames its results as a baseline for understanding current exposure. It notes that custodians and exchanges could reduce risk through improved address practices, reduced key reuse, and migration planning.

The findings come amid rapid global progress in quantum computing research and ongoing debate within the Bitcoin developer community about possible protocol upgrades. These include proposals such as BIP-360, which would introduce more quantum-resistant transaction formats, and other suggestions that could freeze un-migrated coins after a deadline.

Estimates for the arrival of a so-called “Q-Day”—when quantum computing becomes powerful enough to break blockchain cryptography—range from 2030 to 2032 or later. On Thursday, the United States government also announced plans to invest over $2 billion into quantum startups and related infrastructure.

News.Az 

By Nijat Babayev